Selective retransmission of groupcast data

ABSTRACT

Apparatuses, methods, and systems are disclosed for determining a feedback resource associated with groupcast data. One method includes receiving a configuration associated with a resource pool for PSFCH. The method includes receiving groupcast data via sidelink and determining HARQ feedback based at least in part on the received groupcast data. The method includes determining a PSFCH resource for the HARQ feedback based at least in part on the resource pool for the PSFCH and transmitting the HARQ feedback using the determined PSFCH resource.

FIELD

The subject matter disclosed herein relates generally to wirelesscommunications and more particularly relates to groupcast withbeamformed selective transmission/retransmission.

BACKGROUND

The following abbreviations are herewith defined, at least some of whichare referred to within the following description: Third GenerationPartnership Project (“3GPP”), Fifth Generation Core Network (“5CG”),Fifth Generation System (“5GS”), Absolute Radio Frequency Channel Number(“ARFCN”), Authentication, Authorization and Accounting (“AAA”), Accessand Mobility Management Function (“AMF”), Access to Restricted LocalOperator Services (“ARLOS”), Positive Acknowledgment (“ACK”),Application Programming Interface (“API”), Authentication Center(“AuC”), Access Stratum (“AS”), Autonomous Uplink (“AUL”), AUL DownlinkFeedback Information (“AUL-DFP”), Base Station (“BS”), Binary PhaseShift Keying (“BPSK”), Bandwidth Part (“BWP”), Cipher Key (“CK”), ClearChannel Assessment (“CCA”), Control Element (“CE”), Cyclic Prefix(“CP”), Cyclical Redundancy Check (“CRC”), Channel State Information(“CSI”), Common Search Space (“CSS”), Connection Mode (“CM”, this is aNAS state in 5GS), Core Network (“CN”), Control Plane (“CP”), Data RadioBearer (“DRB”), Discrete Fourier Transform Spread (“DFTS”), DownlinkControl Information (“DCI”), Downlink (“DL”), Downlink Pilot Time Slot(“DwPTS”), Dual Connectivity (“DC”), Dual Registration mode (“DR mode”),Discontinuous Transmission (“DTX”), Enhanced Clear Channel Assessment(“eCCA”), Enhanced Licensed Assisted Access (“eLAA”), Enhanced MobileBroadband (“eMBB”), Evolved Node-B (“eNB”), Evolved Packet Core (“EPC”),Evolved Packet System (“EPS”), EPS Mobility Management (“EMM”, this is aNAS state in EPS), Evolved UMTS Terrestrial Radio Access (“E-UTRA”),E-UTRA Absolute Radio Frequency Channel Number (“EARFCN”), Evolved UMTSTerrestrial Radio Access Network (“E-UTRAN”), EuropeanTelecommunications Standards Institute (“ETSI”), Frame Based Equipment(“FBE”), Frequency Division Duplex (“FDD”), Frequency Division MultipleAccess (“FDMA”), Frequency Division Orthogonal Cover Code (“FD-OCC”),General Packet Radio Service (“GPRS”), Generic Public Service Identifier(“GPSI”), Guard Period (“GP”), Global System for Mobile Communications(“GSM”), Globally Unique Temporary UE Identifier (“GUTI”), HybridAutomatic Repeat Request (“HARQ”), Home Subscriber Server (“HSS”), HomePublic Land Mobile Network (“HPLMN”), Information Element (“IE”),Integrity Key (“IK”), Internet-of-Things (“IoT”), International MobileSubscriber Identity (“IMSI”), Key Derivation Function (“KDF”), LicensedAssisted Access (“LAA”), Load Based Equipment (“LBE”),Listen-Before-Talk (“LBT”), Long Term Evolution (“LTE”), Multiple Access(“MA”), Mobility Management (“MM”), Mobility Management Entity (“MME”),Modulation Coding Scheme (“MCS”), Machine Type Communication (“MTC”),Multiple Input Multiple Output (“MIMO”), Mobile Station InternationalSubscriber Directory Number (“MSISDN”), Multi User Shared Access(“MUSA”), Narrowband (“NB”), Negative Acknowledgment (“NACK”) or(“NAK”), New Generation (5G) Node-B (“gNB”), New Generation Radio AccessNetwork (“NG-RAN”, a RAN used for 5GS networks), New Radio (“NR”, a 5Gradio access technology; also referred to as “5G NR”), Next Hop (NH”),Next Hop Chaining Counter (“NCC”), Non-Access Stratum (“NAS”), NetworkExposure Function (“NEF”), Non-Orthogonal Multiple Access (“NOMA”),Network Slice Selection Assistance Information (“NSSAI”), Operation andMaintenance System (“OAM”), Orthogonal Frequency Division Multiplexing(“OFDM”), Packet Data Unit (“PDU”, used in connection with ‘FIDUSession’), Packet Switched (“PS”, e.g., Packet Switched domain or PacketSwitched service), Primary Cell (“PCell”), Physical Broadcast Channel(“PBCH”), Physical Cell Identity (“PCI”), Physical Downlink ControlChannel (“PDCCH”), Physical Downlink Shared Channel (“PDSCH”), PatternDivision Multiple Access (“PDMA”), Physical Hybrid ARQ Indicator Channel(“PHICH”), Physical Random Access Channel (“PRACH”), Physical ResourceBlock (“PRB”), Physical Uplink Control Channel (“PUCCH”), PhysicalUplink Shared Channel (“PUSCH”), Public Land Mobile Network (“PLMN”),Quality of Service (“QoS”), Quadrature Phase Shift Keying (“QPSK”),Radio Access Network (“RAN”), Radio Access Technology (“RAT”), RadioResource Control (“RRC”), Random-Access Channel (“RACH”), Random AccessResponse (“RAR”), Radio Network Temporary Identifier (“RNTI”), ReferenceSignal (“RS”), Registration Area (“RA”, similar to tacking area listused in LTE/EPC), Registration Management (“RM”, refers to NAS layerprocedures and states), Remaining Minimum System Information (“RMSI”),Resource Spread Multiple Access (“RSMA”), Round Trip Time (“RTT”),Receive (“RX”), Radio Link Control (“RLC”), Sparse Code Multiple Access(“SCMA”), Scheduling Request (“SR”), Single Carrier Frequency DivisionMultiple Access (“SC-FDMA”), Secondary Cell (“SCell”), Shared Channel(“SCH”), Session Management (“SM”), Session Management Function (“SMF”),Service Provider (“SP”), Signal-to-Interference-Plus-Noise Ratio(“SINR”), Single Network Slice Selection Assistance Information(“S-NSSAI”), Single Registration mode (“SR mode”), Sounding ReferenceSignal (“SRS”), System Information Block (“SIB”), Synchronization Signal(“SS”), Supplementary Uplink (“SUL”), Sub scriber Identification Module(“SIM”), Tracking Area (“TA”), Transport Block (“TB”), Transport BlockSize (“TB S”), Time-Division Duplex (“TDD”), Time Division Multiplex(“TDM”), Time Division Orthogonal Cover Code (“TD-OCC”), TransmissionTime Interval (“TTI”), Transmit (“TX”), Unified Access Control (“UAC”),Unified Data Management (“UDM”), User Data Repository (“UDR”), UplinkControl Information (“UCI”), User Entity/Equipment (Mobile Terminal)(“UE”), UE Configuration Update (“UCU”), UE Route Selection Policy(“URSP”), Uplink (“UL”), User Plane (“UP”), Universal MobileTelecommunications System (“UMTS”), UMTS Sub scriber IdentificationModule (“USIM”), UMTS Terrestrial Radio Access (“UTRA”), UNITSTerrestrial Radio Access Network (“UTRAN”), Uplink Pilot Time Slot(“UpPTS”), Ultra-reliability and Low-latency Communications (“URLLC”),Visited Public Land Mobile Network (“VPLMN”), and WorldwideInteroperability for Microwave Access (“WiMAX”). As used herein,“HARQ-ACK” may represent collectively the ACK and the NACK and DTX. ACKmeans that a TB is correctly received while NACK (or NAK) means a TB iserroneously received. DTX means that no TB was detected.

In certain wireless communication systems, sidelink transmission allowsone UE device to communicate directly with another UE, e.g., viadevice-to-device (“D2D”) communications. In one embodiment, anintermediary UE shares its connection to a base station with another UEvia sidelink transmission. Sidelink communication may be unicast orgroupcast. HARQ feedback for groupcast involves the receiving UE(s) (“RXUE(s)”) sending feedback to the transmitting UE (“TX UE”).

BRIEF SUMMARY

Disclosed are procedures for groupcast communication, e.g., withbeamformed selective transmission/retransmission.

One method performed by a UE includes receiving a configurationassociated with a resource pool for PSFCH. The method includes receivinggroupcast data via sidelink and determining HARQ feedback based at leastin part on the received groupcast data. The method includes determininga PSFCH resource for the HARQ feedback based at least in part on theresource pool for the PSFCH and transmitting the HARQ feedback using thedetermined PSFCH resource.

BRIEF DESCRIPTION OF THE DRAWINGS

A more particular description of the embodiments briefly described abovewill be rendered by reference to specific embodiments that areillustrated in the appended drawings. Understanding that these drawingsdepict only some embodiments and are not therefore to be considered tobe limiting of scope, the embodiments will be described and explainedwith additional specificity and detail through the use of theaccompanying drawings, in which:

FIG. 1 is a schematic block diagram illustrating one embodiment of awireless communication system for selective retransmission of groupcastdata;

FIG. 2 is a diagram illustrating one embodiment of groupcast withbeamforming for initial transmission;

FIG. 3 is a flowchart diagram illustrating one embodiment of a procedurefor groupcast with selective retransmission;

FIG. 4 is a diagram illustrating one embodiment of Rx UE transmittingboth HARQ feedback and beam/signal feedback;

FIG. 5 is a diagram illustrating one embodiment of Tx UE retransmittingwith unicast beamforming;

FIG. 6 is a diagram illustrating one embodiment of a call flow forgroupcast transmission;

FIG. 7 is a diagram illustrating another embodiment of Rx UEtransmitting both HARQ feedback and beam/signal feedback;

FIG. 8 is a diagram illustrating one embodiment of a network functionapparatus that may be used for selective retransmission of groupcastdata;

FIG. 9 is a diagram illustrating one embodiment of a network functionapparatus that may be used for groupcast with beamformed selectivetransmission/retransmission;

FIG. 10 is a flowchart diagram illustrating one embodiment of a methodfor selective retransmission of groupcast data;

FIG. 11 is a flowchart diagram illustrating one embodiment of a methodfor selective retransmission of groupcast data; and

FIG. 12 is a flowchart diagram illustrating one embodiment of a methodperformed by a UE in accordance with aspects of the present disclosure.

DETAILED DESCRIPTION

As will be appreciated by one skilled in the art, aspects of theembodiments may be embodied as a system, apparatus, method, or programproduct. Accordingly, embodiments may take the form of an entirelyhardware embodiment, an entirely software embodiment (includingfirmware, resident software, micro-code, etc.) or an embodimentcombining software and hardware aspects.

For example, the disclosed embodiments may be implemented as a hardwarecircuit comprising custom very-large-scale integration (“VLSI”) circuitsor gate arrays, off-the-shelf semiconductors such as logic chips,transistors, or other discrete components. The disclosed embodiments mayalso be implemented in programmable hardware devices such as fieldprogrammable gate arrays, programmable array logic, programmable logicdevices, or the like. As another example, the disclosed embodiments mayinclude one or more physical or logical blocks of executable code whichmay, for instance, be organized as an object, procedure, or function.

Furthermore, embodiments may take the form of a program product embodiedin one or more computer readable storage devices storing machinereadable code, computer readable code, and/or program code, referredhereafter as code. The storage devices may be tangible, non-transitory,and/or non-transmission. The storage devices may not embody signals. Ina certain embodiment, the storage devices only employ signals foraccessing code.

Any combination of one or more computer readable medium may be utilized.The computer readable medium may be a computer readable storage medium.The computer readable storage medium may be a storage device storing thecode. The storage device may be, for example, but not limited to, anelectronic, magnetic, optical, electromagnetic, infrared, holographic,micromechanical, or semiconductor system, apparatus, or device, or anysuitable combination of the foregoing.

More specific examples (a non-exhaustive list) of the storage devicewould include the following: an electrical connection having one or morewires, a portable computer diskette, a hard disk, a random-access memory(“RAM”), a read-only memory (“ROM”), an erasable programmable read-onlymemory (“EPROM” or Flash memory), a portable compact disc read-onlymemory (“CD-ROM”), an optical storage device, a magnetic storage device,or any suitable combination of the foregoing. In the context of thisdocument, a computer readable storage medium may be any tangible mediumthat can contain or store a program for use by or in connection with aninstruction execution system, apparatus, or device.

Code for carrying out operations for embodiments may be any number oflines and may be written in any combination of one or more programminglanguages including an object-oriented programming language such asPython, Ruby, Java, Smalltalk, C++, or the like, and conventionalprocedural programming languages, such as the “C” programming language,or the like, and/or machine languages such as assembly languages. Thecode may execute entirely on the user's computer, partly on the user'scomputer, as a stand-alone software package, partly on the user'scomputer and partly on a remote computer or entirely on the remotecomputer or server. In the latter scenario, the remote computer may beconnected to the user's computer through any type of network, includinga local area network (“LAN”) or a wide area network (“WAN”), or theconnection may be made to an external computer (for example, through theInternet using an Internet Service Provider).

Reference throughout this specification to “one embodiment,” “anembodiment,” or similar language means that a particular feature,structure, or characteristic described in connection with the embodimentis included in at least one embodiment. Thus, appearances of the phrases“in one embodiment,” “in an embodiment,” and similar language throughoutthis specification may, but do not necessarily, all refer to the sameembodiment, but mean “one or more but not all embodiments” unlessexpressly specified otherwise. The terms “including,” “comprising,”“having,” and variations thereof mean “including but not limited to,”unless expressly specified otherwise. An enumerated listing of itemsdoes not imply that any or all of the items are mutually exclusive,unless expressly specified otherwise. The terms “a,” “an,” and “the”also refer to “one or more” unless expressly specified otherwise.

As used herein, a list with a conjunction of “and/or” includes anysingle item in the list or a combination of items in the list. Forexample, a list of A, B and/or C includes only A, only B, only C, acombination of A and B, a combination of B and C, a combination of A andC or a combination of A, B and C. As used herein, a list using theterminology “one or more of” includes any single item in the list or acombination of items in the list. For example, one or more of A, B and Cincludes only A, only B, only C, a combination of A and B, a combinationof B and C, a combination of A and C or a combination of A, B and C. Asused herein, a list using the terminology “one of” includes one and onlyone of any single item in the list. For example, “one of A, B and C”includes only A, only B or only C and excludes combinations of A, B andC. As used herein, “a member selected from the group consisting of A, B,and C,” includes one and only one of A, B, or C, and excludescombinations of A, B, and C. As used herein, “a member selected from thegroup consisting of A, B, and C and combinations thereof” includes onlyA, only B, only C, a combination of A and B, a combination of B and C, acombination of A and C or a combination of A, B and C.

Furthermore, the described features, structures, or characteristics ofthe embodiments may be combined in any suitable manner. In the followingdescription, numerous specific details are provided, such as examples ofprogramming, software modules, user selections, network transactions,database queries, database structures, hardware modules, hardwarecircuits, hardware chips, etc., to provide a thorough understanding ofembodiments. One skilled in the relevant art will recognize, however,that embodiments may be practiced without one or more of the specificdetails, or with other methods, components, materials, and so forth. Inother instances, well-known structures, materials, or operations are notshown or described in detail to avoid obscuring aspects of anembodiment.

Aspects of the embodiments are described below with reference toschematic flowchart diagrams and/or schematic block diagrams of methods,apparatuses, systems, and program products according to embodiments. Itwill be understood that each block of the schematic flowchart diagramsand/or schematic block diagrams, and combinations of blocks in theschematic flowchart diagrams and/or schematic block diagrams, can beimplemented by code. This code may be provided to a processor of ageneral-purpose computer, special purpose computer, or otherprogrammable data processing apparatus to produce a machine, such thatthe instructions, which execute via the processor of the computer orother programmable data processing apparatus, create means forimplementing the functions/acts specified in the flowchart diagramsand/or block diagrams.

The code may also be stored in a storage device that can direct acomputer, other programmable data processing apparatus, or other devicesto function in a particular manner, such that the instructions stored inthe storage device produce an article of manufacture includinginstructions which implement the function/act specified in the flowchartdiagrams and/or block diagrams.

The code may also be loaded onto a computer, other programmable dataprocessing apparatus, or other devices to cause a series of operationalsteps to be performed on the computer, other programmable apparatus orother devices to produce a computer implemented process such that thecode which execute on the computer or other programmable apparatusprovide processes for implementing the functions/acts specified in theflowchart diagrams and/or block diagrams.

The flowchart diagrams and/or block diagrams in the Figures illustratethe architecture, functionality, and operation of possibleimplementations of apparatuses, systems, methods, and program productsaccording to various embodiments. In this regard, each block in theflowchart diagrams and/or block diagrams may represent a module,segment, or portion of code, which includes one or more executableinstructions of the code for implementing the specified logicalfunction(s).

It should also be noted that, in some alternative implementations, thefunctions noted in the block may occur out of the order noted in theFigures. For example, two blocks shown in succession may, in fact, beexecuted substantially concurrently, or the blocks may sometimes beexecuted in the reverse order, depending upon the functionalityinvolved. Other steps and methods may be conceived that are equivalentin function, logic, or effect to one or more blocks, or portionsthereof, of the illustrated Figures.

Although various arrow types and line types may be employed in theflowchart and/or block diagrams, they are understood not to limit thescope of the corresponding embodiments. Indeed, some arrows or otherconnectors may be used to indicate only the logical flow of the depictedembodiment. For instance, an arrow may indicate a waiting or monitoringperiod of unspecified duration between enumerated steps of the depictedembodiment. It will also be noted that each block of the block diagramsand/or flowchart diagrams, and combinations of blocks in the blockdiagrams and/or flowchart diagrams, can be implemented by specialpurpose hardware-based systems that perform the specified functions oracts, or combinations of special purpose hardware and code.

The description of elements in each figure may refer to elements ofproceeding figures. Like numbers refer to like elements in all figures,including alternate embodiments of like elements.

Generally, the present disclosure describes systems, methods, andapparatus for groupcast with beamformed selectivetransmission/retransmission for remote units 105 engaged in sidelinkcommunication. In 5G NR, sidelink (“SL”) communication may supportgroupcast transmission and feedback for the groupcast message. Incertain schemes, HARQ feedback for groupcast transmission comprises thereceiver UE transmitting only HARQ NACK. It transmits no signal on PSFCHotherwise. Other schemes for HARQ feedback for groupcast transmissioninclude the receiver UE transmitting both HARQ ACK and HARQ NACKfeedback.

According to Option 1 of HARQ procedures for sidelink (unicast andgroupcast), the Rx UE transmits HARQ-NACK on PSFCH if it fails to decodethe corresponding TB after decoding the associated PSCCH. See 3GPP TR38.885. According to Option 1 of HARQ procedures for sidelink (unicastand groupcast), the Rx UE transmits HARQ-ACK on PSFCH if it successfullydecodes the corresponding TB. It transmits HARQ-NACK on PSFCH if it doesnot successfully decode the corresponding TB after decoding theassociated PSCCH which targets the Rx UE. See 3GPP TR 38.885.

For SL groupcast HARQ feedback signaling, the Physical Sidelink FeedbackChannel (PSFCH) resource may be common to the Rx UEs. Alternatively, thePSFCH resource may be dedicated to each Rx UE. Dedicated resource forACK and NACK transmissions increases the reliability of the groupcasttransmission, but the feedback overhead is very high. However, usingdedicated PSFCH resources allow the feedback information to cover allthe NACK/ACK/DTX cases of all UEs in the group.

In certain embodiments, multiple Rx UEs may share a common PSFCHresource by allowing the failed Rx UEs (i.e., failed to decode thecorresponding TB) to transmit HARQ-NACK on PSFCH, i.e., Option 1. Thisimplies that HARQ-NACK is transmitted in an SFN manner when multiple RxUEs fail to decode a PSSCH which results in reduced overhead forfeedback signaling. There could be a case where some of the Rx UE failedto decode PSCCH, e.g., due to interference, half duplex problem, etc.

Note that the propagation characteristics of FR2 (e.g., 24.25 GHz to52.6 GHz), require the use of beams for V2x sidelink to enable reliabledata transmission and reception which requires sidelink CSI feedbackreporting between the Tx UE and Rx UE. In NR sidelink, the beamreporting can be based on sidelink CSI-RS or sidelink SS/PBCH block.Accordingly, SL CSI feedback contents may include one or more of thefollowing: RSRP, RSRQ, CQI, PMI, RI, CRI/SRI, and Interferenceconditions at Rx side. Moreover, the efficiency and reliability ofretransmission may be improved if the Tx UE receives additional feedbackinformation from Rx UE other than NACK.

FIG. 1 depicts a wireless communication system 100 for groupcast withbeamformed selective transmission/retransmission for wireless devicescommunicating via sidelink communications 125, according to embodimentsof the disclosure. In one embodiment, the wireless communication system100 includes at least one remote unit 105, a radio access network(“RAN”) 120, and a mobile core network 140. The RAN 120 and the mobilecore network 140 form a mobile communication network. The RAN 120 may becomposed of a base unit 110 with which the remote unit 105 communicatesusing wireless communication links 115. Even though a specific number ofremote units 105, base units 110, wireless communication links 115, RANs120, and mobile core networks 140 are depicted in FIG. 1 , one of skillin the art will recognize that any number of remote units 105, baseunits 110, wireless communication links 115, RANs 120, and mobile corenetworks 140 may be included in the wireless communication system 100.

In one implementation, the wireless communication system 100 iscompliant with the system specified in the 3GPP specifications. Moregenerally, however, the wireless communication system 100 may implementsome other open or proprietary communication network, for example, LTEor WiMAX, among other networks. The present disclosure is not intendedto be limited to the implementation of any particular wirelesscommunication system architecture or protocol.

In one embodiment, the remote units 105 may include computing devices,such as desktop computers, laptop computers, personal digital assistants(“PDAs”), tablet computers, smart phones, smart televisions (e.g.,televisions connected to the Internet), smart appliances (e.g.,appliances connected to the Internet), set-top boxes, game consoles,security systems (including security cameras), vehicle on-boardcomputers, network devices (e.g., routers, switches, modems), or thelike. In some embodiments, the remote units 105 include wearabledevices, such as smart watches, fitness bands, optical head-mounteddisplays, or the like. Moreover, the remote units 105 may be referred toas the UEs, subscriber units, mobiles, mobile stations, users,terminals, mobile terminals, fixed terminals, subscriber stations, userterminals, wireless transmit/receive unit (“WTRU”), a device, or byother terminology used in the art.

The remote units 105 may communicate directly with one or more of thebase units 110 in the RAN 120 via uplink (“UL”) and downlink (“DL”)communication signals. Furthermore, the UL and DL communication signalsmay be carried over the wireless communication links 115. Here, the RAN120 is an intermediate network that provides the remote units 105 withaccess to the mobile core network 140.

In some embodiments, the remote units 105 communicate with anapplication server 151 via a network connection with the mobile corenetwork 140. For example, an application 107 (e.g., web browser, mediaclient, telephone/VoIP application) in a remote unit 105 may trigger theremote unit 105 to establish a PDU session (or other data connection)with the mobile core network 140 via the RAN 120. The mobile corenetwork 140 then relays traffic between the remote unit 105 and theapplication server 151 in the packet data network 150 using the PDUsession. Note that the remote unit 105 may establish one or more PDUsessions (or other data connections) with the mobile core network 140.As such, the remote unit 105 may concurrently have at least one PDUsession for communicating with the packet data network 150 and at leastone PDU session for communicating with another data network (not shown).

The base units 110 may be distributed over a geographic region. Incertain embodiments, a base unit 110 may also be referred to as anaccess terminal, an access point, a base, a base station, a Node-B, aneNB, a gNB, a Home Node-B, a relay node, or by any other terminologyused in the art. The base units 110 are generally part of a radio accessnetwork (“RAN”), such as the RAN 120, that may include one or morecontrollers communicably coupled to one or more corresponding base units110. These and other elements of radio access network are notillustrated but are well known generally by those having ordinary skillin the art. The base units 110 connect to the mobile core network 140via the RAN 120.

The base units 110 may serve a number of remote units 105 within aserving area, for example, a cell or a cell sector, via a wirelesscommunication link 115. The base units 110 may communicate directly withone or more of the remote units 105 via communication signals.Generally, the base units 110 transmit DL communication signals to servethe remote units 105 in the time, frequency, and/or spatial domain.Furthermore, the DL communication signals may be carried over thewireless communication links 115. The wireless communication links 115may be any suitable carrier in licensed or unlicensed radio spectrum.The wireless communication links 115 facilitate communication betweenone or more of the remote units 105 and/or one or more of the base units110.

In one embodiment, the mobile core network 140 is a 5G core (“5GC”) orthe evolved packet core (“EPC”), which may be coupled to a packet datanetwork 150, like the Internet and private data networks, among otherdata networks. A remote unit 105 may have a subscription or otheraccount with the mobile core network 140. Each mobile core network 140belongs to a single public land mobile network (“PLMN”). The presentdisclosure is not intended to be limited to the implementation of anyparticular wireless communication system architecture or protocol.

The mobile core network 140 includes several network functions (“NFs”).As depicted, the mobile core network 140 includes multiple user planefunctions (“UPFs”) 145. The mobile core network 140 also includesmultiple control plane functions including, but not limited to, anAccess and Mobility Management Function (“AMF”) 141 that serves the RAN120, a Session Management Function (“SMF”) 143, and a Policy ControlFunction (“PCF”) 147. In certain embodiments, the mobile core network140 may also include an Authentication Server Function (“AUSF”), aUnified Data Management function (“UDM”) 149, a Network RepositoryFunction (“NRF”) (used by the various NFs to discover and communicatewith each other over APIs), or other NFs defined for the 5GC.

In various embodiments, the mobile core network 140 supports differenttypes of mobile data connections and different types of network slices,wherein each mobile data connection utilizes a specific network slice.Here, a “network slice” refers to a portion of the mobile core network140 optimized for a certain traffic type or communication service. Incertain embodiments, the various network slices may include separateinstances of network functions, such as the SMF 143 and UPF 145. In someembodiments, the different network slices may share some common networkfunctions, such as the AMF 141 and UDM 149. The different network slicesare not shown in FIG. 1 for ease of illustration, but their support isassumed.

Although specific numbers and types of network functions are depicted inFIG. 1 , one of skill in the art will recognize that any number and typeof network functions may be included in the mobile core network 140.Moreover, where the mobile core network 140 is an EPC, the depictednetwork functions may be replaced with appropriate EPC entities, such asan MME, S-GW, P-GW, HSS, and the like. In certain embodiments, themobile core network 140 may include a AAA server.

In various embodiments, the remote units 105 may communicate directlywith each other (e.g., device-to-device communication) using sidelink(“SL”) communication signals 125. Here, sidelink transmissions from a“transmitting” remote unit 105 (i.e., Tx UE) may be groupcast orunicast. Groupcast refers to group communications where the transmittingremote unit 105 in the group transits a multicast packet to all itsgroup members, where the members of the group belong to the samedestination group identifier.

In certain embodiments, the transmitting remote unit 105 groupcastsusing an omnidirectional antenna. In other embodiments, the transmittingremote unit 105 groupcasts data using beam sweeping. As used herein,beam sweeping refers to the transmitting remote unit 105 transmittingthe groupcast in predefined directions/beams in sequence, wherein thesequence is indexed and the sequence/index is transmitted as part of thesidelink control channel (e.g., in sidelink control information “SCI”).The transmitting remote unit 105 may dynamically signal (in SCI)information about transmission patterns and periodicity. For example,the transmitting remote unit 105 may transmit a signal (e.g., groupcastmessage) on a first beam during a first set of transmission symbolduration (e.g., first slot), transmit the signal on a second beam duringa second set of transmission symbol duration (e.g., second slot), etc.

In certain embodiments, the transmitting remote unit 105 may conserveresources (e.g., radio/network resources, power, computationalresources, etc.) by performing “partial” beam sweeping where one or morebeams are “skipped” such that no transmission is made and the “skipped”beams are not a part of the beam sweeping pattern. Note that partialbeam sweeping may also reduce latency as compared to full beam sweeping.Again, the transmitting remote unit 105 dynamically signals informationabout the pattern and timing of beam sweeping transmission (full orpartial).

In some embodiments, the transmitting remote unit 105 retransmits thegroupcast data by sending unicast messages to one or more members of thegroup. In various embodiments, the transmitting remote unit 105 performs“N-Unicast” transmission, which refers to the transmitting remote unit105 performing unicast transmission to N receiving remote units 105(e.g., establishing different Unicast links to the N receivers).N-Unicast transmission may occur either on the same or differenttime-frequency resources. Where the same time-frequency resources areused, the transmitting remote unit 105 may use spatial multiplexingtechniques (e.g., beamforming), similar to Multi-User MIMO.

A “receiving” remote unit 105 may provide HARQ feedback to thetransmitting remote unit 105. In various embodiments, SL communicationsignals 125 may be sent on frequencies in the Frequency Range 2 (“FR2”)band, e.g., 24.25 GHz to 52.6 GHz. In some embodiments, SL communicationsignals 125 may be sent on frequencies beyond the Frequency Range 2(“FR2”) band, e.g., using the ITS band at 60 GHz to 70 GHz. SLcommunication signals 125 may include data signals, control information,and/or reference signals. Upon receiving a NACK message corresponding toa groupcast message from a receiving remote unit 105 (Rx UE), thetransmitting remote unit 105 (Tx UE) may selectively retransmit thegroupcast message as described in further detail below. In someembodiments, the transmitting remote unit 105 performs N-Unicast dataretransmission to the receiving remote units 105 with beamforming toenhance the reliability (where N could be equal to 1 if only onereceiving remote units 105 transmit NACK). In some embodiments, thetransmitting remote unit 105 performs groupcast retransmission withpartial beam sweeping or repetition with different beams in thedirection of the subset of receiving remote units 105 to enhance thereliability. Here, the “subset” of receiving remote units 105 refers tosome, but not all receiving remote units 105 (Rx UEs) in the group.

While FIG. 1 depicts components of a 5G RAN and a 5G core network, thedescribed embodiments for groupcast with beamformed selectivetransmission/retransmission apply to other types of communicationnetworks, including IEEE 802.11 variants, GSM, GPRS, UMTS, LTE variants,CDMA 2000, Bluetooth, ZigBee, Sigfoxx, and the like. For example, in anLTE variant involving an EPC, the AMF 135 may be mapped to an MME, theSMF mapped to a control plane portion of a PGW and/or to an MME, the UPFmap to an SGW and a user plane portion of the PGW, the UDM/UDR maps toan HSS, etc.

FIG. 2 depicts a groupcast transmission scenario 200, according toembodiments of the disclosure. The groupcast transmission scenario 200involves a transmitting UE (“Tx UE 205”) 205 sends an initialtransmission 215 to a set of receiving UEs (“Rx UEs 210”) 210. The Tx UE205 and each Rx UE 210 may be an embodiment of the remote unit 105.

The Tx UE 205 sends the initial groupcast transmission 215 to the groupof Rx UEs 210 using beam sweeping. For ease of illustration, four beamsare shown (with beam indices 1-4); however, the Tx UE 205 may transmiton more or few beams. Moreover, while a specific order of transmissionis shown (e.g., specific beam sweeping direction), in other embodimentsthe beams of Tx UE 205 may have different indices and/or thetransmission order may differ from that shown. In some embodiments, thebeam IDs may be locally indexed relative to an antenna panel, withspatial separation for beams with the same beam index from differentantenna panels achieved by the physical separation/placement of theantenna panels. In one embodiment, the beam ID may be a reference signalID such as S-CSI-RS ID or SL-SSB ID. In another embodiment, the beam IDmay be based on sidelink S-CSI-RS or SL-SSB information.

The Tx UE 205 communicates SCI to the Rx UEs 210. In certainembodiments, the SCI is transmitted along with a beam RS prior to thestart of the groupcast transmission. In other embodiments, the Tx UE 205transmits the beam RS (e.g., S-CSI-RS) along with the SCI and groupcastdata transmission that is antenna-port quasi-co-located with the beamRS. In one embodiment, the beam RS is sent on the first symbol of thedata transmission block associated with the beam. In the depictedembodiments, beam sweeping is used to transmit the differenttransmission blocks.

In one example, the SCI and groupcast data transmission QAM symbols arethe same for all or a portion of the beams used for the datatransmission. In another example, a data transmission on a first beammay use a first redundancy version (RV) and the data transmission of asecond beam (different than the first beam) may use a second redundancyversion. In certain embodiments, a Rx UE 210 may combine across multipleTx beams to decode the received groupcast data transmission.

In certain embodiments, two or more transmission blocks are transmittedsimultaneously if the Tx UE 205 supports capability of multiplesimultaneous beams transmission and the Tx UE 205 has sufficient power.Here, the simultaneously transmitted beams may be from a same antennapanel or from different antenna panels (e.g., antenna panels on thefront, back, left side, right side of the vehicles). The number of beamsused for transmission of the data may be different for different antennapanels, e.g., depending on the size of the antenna panels (e.g. numberof antenna elements), directivity and possible launch angles capabilityof the antenna panels, placement of the antenna panels on the vehicle,detection of local surrounding environment around the vehicle containingthe Tx UE 205, e.g., no vehicles on one side, wall or blockage on oneside, road lane in which the vehicle is in, direction of travel. The TxUE 205 may select the number of beams to use based on other assistanceinformation received from the gNB and/or other technologies such asradar/lidar and sensor systems on-vehicle, or information received fromother non-3GPP RATs.

FIG. 3 depicts a procedure 300 for groupcast with beamformed selectivetransmission/retransmission, according to embodiments of the disclosure.The procedure 300 may be performed by a remote unit 105, such as the TxUE 205. The procedure 300 begins with the initial SL groupcasttransmission being triggered by the Tx UE 205 (see block 305). Asdiscussed above with respect to FIG. 2 , the initial groupcasttransmission may use beam sweeping. Upon receiving HARQ feedback fromthe group of Rx UEs 210, the Tx UE 205 determines the number of Rx UEfor which NACK was received, e.g., on dedicated resources (see block310). If only one Rx UE 210 sends NACK feedback, then the Tx UE 205triggers unicast retransmission (see block 315). Where the Rx UE 210sending the NACK (referred to as a “NACK Rx UE 210”) also providessufficient sidelink channel state information (“S-CSI”), such as a beamID (e.g., S-CSI-RS info), then the Tx UE 205 applies beamforming to theUnicast data (e.g., beamforms the retransmission).

However, if more than one Rx UE 210 transmits NACK, then the Tx UE 205triggers retransmission of the data using either groupcast or N-Unicasttransmission (see block 320). For groupcast retransmission, the data maybe sent with partial beamforming or repetition with different beams inthe direction of the NACK Rx UEs 210. Here, retransmission to themultiple NACK Rx UEs 210 may occur in the same time slot. Alternatively,each repetition of the data may be configured at different time slots.Again, where a NACK Rx UE 210 provides sufficient S-CSI, then the Tx UE205 may apply beamforming to the retransmission.

In various embodiments, the UEs (e.g., Tx UE 205 and Rx UEs 210) are(pre)configured with the sidelink groupcast HARQ retransmission profileused to select the retransmission mode (e.g., groupcast or N-Unicasttransmission) based on at least one of the QoS priority and the numberof NACK(s). In one embodiment, the gNB/eNB (e.g., base unit 110) or ascheduling UE may configure the sidelink groupcast HARQ retransmissionprofile. In another embodiment, the Tx UE 205 autonomously decides thesidelink groupcast HARQ retransmission profile based on the priority ofthe transmission and/or congestion metric, interference value, etc.

The Tx UE 205 indicates in the SCI bit about one of the various optionsof the feedback requested from the Rx UE 210(s) such as: a) Rx UE 210 isto transmit only HARQ NACK on the common sidelink feedback resource; b)Rx UE 210 is to transmit HARQ ACK/NACK on a dedicated sidelink feedbackresource; or c) Rx UE 210 is to transmit HARQ NACK+S-CSI information ona dedicated feedback resource. In certain embodiments, the commonsidelink feedback resource to use is indicated in the SCI. In certainembodiments, the dedicated sidelink feedback resource to use isindicated in the SCI.

In one example, the dedicated sidelink feedback resource may be a poolof feedback resources, and the Rx UE 210 selects a resource for HARQfeedback from the indicated pool of resources (e.g., based on Rx UE 210ID or SL ID). The pool of feedback resources may be indicated by thegNB, may be indicated by the TX UE 205 in the SCI, or may be determinedbased on the SCI information. For example, the gNB may configure andindicate a first pool of feedback resources, and a second pool offeedback resources (which is a subset of the first pool of feedbackresources) may be determined based on e.g., QoS priority which may beindicated in the SCI.

The Tx UE 205 may dynamically configure in SCI during retransmissionfrom common SL feedback to dedicated SL feedback or from dedicated SLfeedback to a subset of dedicated SL feedback based on certain policylike number of NACK(s) received, etc. In one embodiment, the differentPSFCH format which could be based on HARQ ACK/NACK or S-CSI can bedynamically configured during retransmission in SCI.

In one embodiment, the Tx UE 205 uses the Uu interface (gNB to UEcommunication) TA (Timing Advance) value for SL transmission (as done inLTE V2V), i.e., TA value used relative to received Uu interface DLtiming is used for SL transmission. Here, the Tx UE 205 may include theTA (Timing Advance) value it uses in the SCI. The Rx UE 210 (Rx UE 210)may estimate the TA or the propagation delay to the SL Tx UE based onthe TA value of the Tx UE 205 and the TA value of Uu interface of the RxUE 210.

Tx UE 205 transmit-timing relative to Rx UE 210 Uu transmit-timing maybe calculated as: (TA₁−TA₂)/2, where TA₁ is the Uu TA for the Rx UE 210transmit-timing, and TA₂ is the Tx UE 205 TA. The Rx UE 210 maydetermine the SL receive-timing relative to its Uu Tx transmit-timing asT_(SL,Rx) based on the received SL. Here, a positive value represents adelay relative to Uu Tx transmit-timing, while a negative valuerepresents an advance relative to Uu Tx transmit-timing.

Additionally, the Rx UE 210 may determine the propagation delay to theTx UE 205 based on T_(SL,Rx) and (TA₁−TA₂)/2, for example calculated as:T_(p12)=T_(SL,Rx)−(TA₁−TA₂)/2. Further, a known offset may be applied tothe T_(p12) value to allow for different SL Tx and Rx slot boundariesand a corresponding TA value for the feedback Tx may be determined.Accordingly, the Rx UEs 210 SL feedback transmissions (e.g., on commonor dedicated feedback resources) may be time-aligned at the Tx UE 205receiver and be received within the CP duration.

The use of a different TA value from the TA value used for Uu for the RxUE 210 transmission e.g., feedback channel (or generally for anytransmission where the Rx UE 210 is expected to receive simultaneoustransmission from more than one UEs), may be beneficial when the SLcoverage area is relatively large (e.g. >100 m), so that the Rx UE 210transmissions signals sent to the Tx UE 205 are received well within theCP, and not/minimally sacrifice the max channel-delay spread protectionof the CP.

Because the propagation characteristics of FR2 is susceptible toblockage and require the use of beams for reliable data transmission andreception, sidelink CSI feedback reporting may be required between theTx UE 205 and Rx UE 210(s). One example of S-CSI feedback reporting isthe Rx UE 210 reporting best beam ID. Here, the sidelink receive beam IDmay be based on sidelink S-CSI-RS or SL-SSB information. The beam ID mayalso be a reference signal ID such as S-CSI-RS ID or SL-SSB ID.

FIG. 4 depicts a feedback scenario 400, according to embodiments of thedisclosure. The feedback scenario 400 involves the Tx UE 205 sending agroupcast transmission 405 to the group of Rx UEs 210 and at least oneRx UE 210 sending “enhanced” feedback 410. The groupcast transmission405 may be sent using beamsweeping or using a plurality of wider beams.Here, the enhanced feedback 410 includes a HARQ ACK or NACK indication(or HARQ-NACK indication), and/or a best beam ID used for transmissionby the Tx UE 205 and S-CSI information.

In one example, the feedback information may include of locationinformation or information from which the location of Rx UE 210 can beinferred by the Tx UE 205. In one example, the information may be globallocation coordinates of Rx UE 210. In another example, the informationmay be relative positioning information such as spatial and angularmeasurements (Angle-of-Arrival/Angle-of-Departure) e.g., for the latestreceived transmission from Tx UE 205. The Tx UE 205 can use suchlocation information to beamform in the desired direction of the Rx UE210.

In one example, the feedback information may include recommendation onrelative transmit power (to power level used for current/latesttransmission) for the retransmission, e.g., −1, 0, +1, +3 dB powerchange. The retransmission data may use a different redundancy version(RV) that the initial (first) transmission, which may be indicated inthe SCI information. In one example, the initial (first) transmissionand the retransmission may each be self-decodable. In one example, theretransmission power level may be different than the initialtransmission power level. The difference may be dependent on the QoSpriority of the data.

In some embodiments, the Tx UE 205 transmits SCI indicating the beamindices in the initial groupcast transmission that correspond to thegroupcast data transmission. Here, the Beam information could beS-CSI-RS or a Reference signal identifier (e.g. an explicit value or animplicit Index value in the order of appearance in the list) before oralong with the initial groupcast data transmission. The transmissionoccasion includes the time slot/symbols of the data and/or S-CSI-RS/anyRS using different beam ID is dynamically or semi statically signaled.

In some embodiments, the Tx UE 205 transmits the beam RS (e.g.,S-CSI-RS) (e.g., with beam sweeping on each of the beams) prior to thestart of the groupcast data transmission. In certain embodiments, SCI istransmitted together with the beam RS prior to the start of thegroupcast data transmission. The number of beams used for the groupcastmay be included in the SCI. The beam RS scrambling sequence may be basedon the SL UE ID, and/or the symbol/slot index, and/or the beam index.The SCI associated with the beam RS may include the beam ID used for thetransmission.

In various embodiments, the Rx UE 210 determines the best Rx beam to usefor reception of the groupcast data transmission based on the receivedbeam RSs. In certain embodiments, a known offset or offset between thebeam RS transmission and the groupcast data transmission may beindicated in the SCI information. In one example, the offset isdetermined based on the number of beams used for the groupcast which isindicated in the SCI, e.g., the groupcast data transmission in symbolblock n (or data transmission index n) is antenna-port quasi-co-locatedwith the beam RS sent in symbol block n-N, where N is the number ofbeams indicated in the SCI. A symbol block can include one or symbols.

In other embodiments, the Tx UE 205 transmits the beam RS (e.g.,S-CSI-RS) along with the SCI and groupcast data transmission that isantenna-port quasi-co-located with the beam RS. In certain embodiments,the beam RS is sent on a first symbol of the data transmission blockassociated with the beam.

As discussed above, the Tx UE 205 may use beam sweeping to transmit thedifferent transmission blocks. In one example, the SCI and groupcastdata transmission QAM symbols are the same for all or a portion of thebeams used for the data transmission. In another example, a datatransmission on a first beam may use a first redundancy version (RV) andthe data transmission of a second beam (different than the first beam)may use a second redundancy version. In one example, the Rx UE 210 maycombine across multiple beams to decode the received groupcast datatransmission.

In one example, two or more transmission blocks may be transmittedsimultaneously if the Tx UE 205 supports capability of multiplesimultaneous beams transmission and the UE has sufficient power. Thesimultaneous transmitted beams may be from a same antenna panel ordifferent antenna panels (e.g., antenna panels on the front, back, leftside, right side of the vehicles). The number of beams used fortransmission of the data may be different for different antenna panelse.g., depending on the size of the antenna panels (e.g. number ofantenna elements), directivity and possible launch angles capability ofthe antenna panels, placement of the antenna panels on the vehicle,detection of local surrounding environment around the vehicle e.g., novehicles on one side, wall or blockage on one side, road lane in whichthe vehicle is in, direction of travel. The UE may make decision on thenumber of beams to use based on other assistance information receivedfrom the gNB and/or other technologies such as radar/lidar and sensorsystems on-vehicle, or information received from other non-3GPP RATs.

In various embodiments, groupcast data (along with S-CSI-RS or any RS)are being transmitted with a certain interval by the Tx UE 205. Thegroupcast may be transmitted via a specific beam radiated in a certaindirection. Each data transmission may be identified by a unique numbercalled data transmission index (DTI) which are indexed from ascendingorder in time from 0 to L−1 and dynamically signaled within SCI. Asdepicted in FIGS. 2 and 4 , multiple Rx UEs 210 are located around Tx UE205. Each Rx UE 210 measures the signal strength based on the RS itdetected for a certain period and identifies the best beam with thestrongest signal strength. If the decoding fails at a Rx UE 210 for oneof the Data (PSSCH) packet, then that Rx UE 210 sends feedback NACK bitsalong with the best beam ID and/or the corresponding received signalstrength. In various embodiments, the feedback is sent on dedicatedresources. The dedicated resources may be semi-statically configured bythe gNB/eNB or by another scheduling UE in the same group for everyPSFCH formats and provided to all UEs in the group. The feedbackinformation can also include CSI information like PMI, covariance matrixetc., as described above.

In certain embodiments, the Tx UE 205 may explicitly specify a certainPSFCH format in the SCI for feedback. Additionally, the Rx UE 210(s) 210may implicitly or explicitly feedback for an omni-directionaltransmission, for example by not providing the best beam information. Insome embodiments, the Rx UE 210 may provide the feedback using atransmit beam using a spatial transmission filter corresponding toreceive spatial domain transmission filter for receiving the datatransmission (e.g., transmit with the same spatial domain transmissionfilter used for the reception of the groupcast data transmission andbeam RS and UE capable of beam correspondence).

FIG. 5 depicts a retransmission scenario 500, according to embodimentsof the disclosure. The retransmission scenario 500 involves the Tx UE205 sending a second transmission 505 of the groupcast data to a subsetof the Rx UEs 210 (e.g., after receiving the HARQ NACK feedback). Here,the Tx UE 205 sends to those Rx UEs from which HARQ NACK feedback wasreceived. Here, the Tx UE 205 has received a NACK and additionalfeedback information, as described above with reference to FIG. 4 , forone or more of the Rx UEs 210.

In one case, the second transmission is a retransmission with differentredundancy version (e.g., where each RV is self-decodable). In anothercase, the Tx UE 205 transmits a first beam with one RV and second beam(different than first one) with second RV without waiting for thefeedback. In various embodiments, the Tx UE 205 selectively retransmitsdata to a subset of the Rx UEs 210.

In some embodiments, the Tx UE 205 may retransmit with unicasttransmission. From the additional feedback information, the Tx UE 205knows the best beam ID of the Rx UE 210(s) that transmit NACK(s) (orother suitable feedback information) and thus can establish the unicastbeam in the direction of Rx UE 210(s). The Tx UE 205 may retransmitusing N-Unicast to the subset comprising N Rx UEs 210. In the depictedembodiment, a first unicast retransmission 510 is sent to theupper-right Rx UE 210 and a second unicast retransmission 515 is sent tothe lower-right Rx UE 210, in response to both Rx UEs 210 sending NACKto the Tx UE 205.

In other embodiments, the Tx UE 205 may retransmit using partial beamsweeping as described above. Here, the Tx UE 205 uses the best beam ID(or other suitable feedback information) to identify which beams to skipwhen retransmitting.

FIG. 6 depicts a call flow 600 for selective retransmission, accordingto embodiments of the disclosure. The call flow involves four UEs (i.e.,UE1 605, UE2 610, UE3 615, and UE4 620) using groupcast communication.Each UE may be an embodiment of the remote unit 105 described above.

After establishing the groupcast communication 625, the UE1 605 (e.g.,the Tx UE) sends groupcast SCI 630 to the group. Notably, the groupcastSCI 630 contains a PSFCH format indicator, a data transmission index(“DTI”) value, and a transmission occasion value. The UE1 605 also sendsgroupcast data 635 (e.g., using beam sweeping, as described above).

In the depicted embodiment, the UE2 610 receives and successfullydecodes the groupcast data; however, the UE3 615 and UE4 620 fail tosuccessfully decode the groupcast data (see failed receptions 640 and645). The UE3 615 and UE4 620 each determine S-CSI information(including best beam ID) and transmit sidelink feedback contentinformation (“SFCI”) to the UE1 605 containing NACK and S-CSI feedback(see SFCI 650 and 655).

The UE1 605 sends second SCI 660 (e.g., to the subset UE3-UE4)containing PSFCH format indicator, a DTI value, and a transmissionoccasion value. Additionally, the UE1 605 uses the S-CSI feedback fromUE3 615 and UE4 620 to selectively retransmit the groupcast data to UE3615 and UE4 620. In one embodiment, the UE1 uses partial beam sweeping665 to retransmit the data. In other embodiments, instead ofretransmitting using beam sweeping, the UE1 605 uses N-Unicast toretransmit the data. Here, the UE1 605 may use the S-CSI information toestablish unicast beams in the direction of UE3 615 and UE4 620.

FIG. 7 depicts a second Rx UE 210 feedback scenario 700, according toembodiments of the disclosure. The Rx UE 210 feedback scenario 700involves the Tx UE 205 sending a groupcast transmission 705 to the groupof Rx UEs 210. Here, the groupcast transmission 705 corresponds to theinitial transmission of groupcast data. In certain embodiments, thegroupcast transmission is achieved using beam sweeping. In certainembodiments, the groupcast transmission is sent using over a pluralityof (wider) beams.

In the scenario 700, at least one Rx UE 210 does not successfully decodethe groupcast signal. Here, the upper-right hand Rx UE 210 fails todecode the groupcast TB. Accordingly, the Rx UE 210 sends “enhanced”NACK feedback 710. Here, the enhanced feedback 710 may be as describedabove with reference to FIG. 4 and may include, for example, a HARQACK/NACK indication, a best beam ID and S-CSI information.

Additionally, in the scenario 700, the Rx UE(s) 210 transmits the NACKfeedback 710 using beam sweeping, i.e., transmitting the NACK(s) usingone or more beams towards the Tx UE 205 in the same or different timeslot. In this case, the Rx UE 210(s) can transmit the NACK(s) on adedicated resource which are semi-statically configured. Additionally,the configuration of periodicity/time slot may be semi-static or(pre)configured. In some embodiments, the Tx UE 205 determines the bestbeam ID for retransmission based on the enhanced feedback 710 from theRx UE 210. In other embodiments, the Tx UE 205 implicitly determines thebest beam from the HARQ-ACK or HARQ-NACK reception from the Rx UE 210.

FIG. 8 depicts a user equipment apparatus 800 that may be used forgroupcast with beamformed selective transmission/retransmission,according to embodiments of the disclosure. In various embodiments, theuser equipment apparatus 800 is used to implement one or more of thesolutions described above. The user equipment apparatus 800 may be oneembodiment of the AMF, described above. Furthermore, the user equipmentapparatus 800 may include a processor 805, a memory 810, an input device15, an output device 820, and a transceiver 825. In some embodiments,the input device 815 and the output device 820 are combined into asingle device, such as a touchscreen. In certain embodiments, the userequipment apparatus 800 may not include any input device 815 and/oroutput device 820. In various embodiments, the user equipment apparatus800 may include one or more of: the processor 805, the memory 810, andthe transceiver 825, and may not include the input device 815 and/or theoutput device 820.

The processor 805, in one embodiment, may include any known controllercapable of executing computer-readable instructions and/or capable ofperforming logical operations. For example, the processor 805 may be amicrocontroller, a microprocessor, a central processing unit (“CPU”), agraphics processing unit (“GPU”), an auxiliary processing unit, a fieldprogrammable gate array (“FPGA”), or similar programmable controller. Insome embodiments, the processor 805 executes instructions stored in thememory 810 to perform the methods and routines described herein. Theprocessor 805 is communicatively coupled to the memory 810, the inputdevice 815, the output device 820, and the transceiver 825.

In various embodiments, the user equipment apparatus 800 performssidelink communication (e.g., via the transceiver 825). Here, theprocessor 805 may controls the user equipment apparatus 800 to achievethe UE behaviors described herein.

In some embodiments, the user equipment apparatus 800 is a Tx UE 205. Insuch embodiments, the transceiver 825 transmits groupcast data viasidelink communication to a set of UEs (e.g., Rx UEs 210) and receivesnegative acknowledgement feedback via sidelink communication from atleast one UE of the set, the negative acknowledgement feedbackindicating unsuccessful reception of the groupcast data. The processor805 may then determine a retransmission mode based on a number of UEssending negative acknowledgement feedback. Further, the processor 805controls the transceiver 825 to send selectively beamformedretransmission of the groupcast data according to the determinedretransmission mode.

In certain embodiments, the retransmission(s) of the groupcast datais/are only sent to those UEs that transmitted negative acknowledgementfeedback. In one embodiment, the retransmission mode is unicastretransmission with beamforming. In another embodiment, theretransmission mode is groupcast with partial beam sweeping. In someembodiments, the processor 805 further determines the retransmissionmode based on a QoS priority of the groupcast data.

In some embodiments, the transceiver 825 receives a sidelink groupcastHARQ retransmission profile from a base station in a mobilecommunication network (e.g., a RAN node, such as gNB or eNB). In variousembodiments, the sidelink communication does not pass through the basestation. In certain embodiments, the base station indicates a pool offeedback resources for sidelink communication.

In various embodiments, transmitting the groupcast data includes thetransceiver 825 transmitting two or more data TBs simultaneously usingdifferent antenna panels. In some embodiments, the transceiver 825further transmits SCI to the set of UEs. In certain embodiments, the SCIincludes a data transmission index and a transmission occasion. Incertain embodiments, the SCI indicates a PSFCH format for feedback. Insuch embodiments, the at least one UE transmits the negativeacknowledgement using the indicated PSFCH format.

In some embodiments, receiving negative acknowledgement feedbackincludes receiving best beam information from the at least one UE. Insuch embodiments, the processor 805 may select one or more beams usingthe best beam information. In further embodiments, sending selectivelybeamformed retransmission of the groupcast data includes the transceiver825 retransmitting on the selected one or more beams.

In some embodiments, receiving negative acknowledgement feedbackincludes receiving location information for the at least one UE. In suchembodiments, the processor 805 may select one or more beams using thelocation information. In further embodiments, sending selectivelybeamformed retransmission of the groupcast data includes the transceiver825 retransmitting on the selected one or more beams.

In some embodiments, the user equipment apparatus 800 is a Tx UE 205. Insuch embodiments, the transceiver 825 receives a groupcast signal from aTx UE 205 and the processor 805 detects the unsuccessful decoding thegroupcast signal. The processor 805 then determines best beaminformation and sends feedback to the Tx UE 205 via the transceiver 825.Here, the feedback includes a negative acknowledgement and the best beaminformation.

In some embodiments, the transceiver 825 receives a sidelink referencesignal associated with the groupcast signal and the processor 805derives the best beam information using the sidelink reference signal.

In some embodiments, the transceiver 825 receives SCI prior to receivingthe groupcast signal. In such embodiments, the SCI may be receivedtogether with a sidelink reference signal associated with the groupcastsignal.

In some embodiments sending feedback to the Tx UE 205 includestransmitting the feedback towards the Tx UE 205 using beam sweeping. Insome embodiments, the feedback includes sidelink channel stateinformation.

The memory 810, in one embodiment, is a computer readable storagemedium. In some embodiments, the memory 810 includes volatile computerstorage media. For example, the memory 810 may include a RAM, includingdynamic RAM (“DRAM”), synchronous dynamic RAM (“SDRAM”), and/or staticRAM (“SRAM”). In some embodiments, the memory 810 includes non-volatilecomputer storage media. For example, the memory 810 may include a harddisk drive, a flash memory, or any other suitable non-volatile computerstorage device. In some embodiments, the memory 810 includes bothvolatile and non-volatile computer storage media.

In some embodiments, the memory 810 stores data related to groupcastwith beamformed selective transmission/retransmission. For example, thememory 810 may store beam indices, CSI information, HARQ feedback,groupcast data, and the like. In certain embodiments, the memory 810also stores program code and related data, such as an operating systemor other controller algorithms operating on the remote unit 105.

The input device 815, in one embodiment, may include any known computerinput device including a touch panel, a button, a keyboard, a stylus, amicrophone, or the like. In some embodiments, the input device 815 maybe integrated with the output device 820, for example, as a touchscreenor similar touch-sensitive display. In some embodiments, the inputdevice 815 includes a touchscreen such that text may be input using avirtual keyboard displayed on the touchscreen and/or by handwriting onthe touchscreen. In some embodiments, the input device 815 includes twoor more different devices, such as a keyboard and a touch panel.

The output device 820, in one embodiment, is designed to output visual,audible, and/or haptic signals. In some embodiments, the output device820 includes an electronically controllable display or display devicecapable of outputting visual data to a user. For example, the outputdevice 820 may include, but is not limited to, an LCD display, an LEDdisplay, an OLED display, a projector, or similar display device capableof outputting images, text, or the like to a user. As another,non-limiting, example, the output device 820 may include a wearabledisplay separate from, but communicatively coupled to, the rest of theuser equipment apparatus 800, such as a smart watch, smart glasses, aheads-up display, or the like. Further, the output device 820 may be acomponent of a smart phone, a personal digital assistant, a television,a table computer, a notebook (laptop) computer, a personal computer, avehicle dashboard, or the like.

In certain embodiments, the output device 820 includes one or morespeakers for producing sound. For example, the output device 820 mayproduce an audible alert or notification (e.g., a beep or chime). Insome embodiments, the output device 820 includes one or more hapticdevices for producing vibrations, motion, or other haptic feedback. Insome embodiments, all or portions of the output device 820 may beintegrated with the input device 815. For example, the input device 815and output device 820 may form a touchscreen or similar touch-sensitivedisplay. In other embodiments, the output device 820 may be located nearthe input device 815.

As discussed above, the transceiver 825 communicates with one or moreUEs via sidelink. Additionally, the transceiver 825 communicates withone or more network functions of a mobile communication network via oneor more access networks. The transceiver 825 operates under the controlof the processor 805 to transmit messages, data, and other signals andalso to receive messages, data, and other signals. For example, theprocessor 805 may selectively activate the transceiver 825 (or portionsthereof) at particular times in order to send and receive messages.

The transceiver 825 may include one or more transmitters 830 and one ormore receivers 835. Although only one transmitter 830 and one receiver835 are illustrated, the user equipment apparatus 800 may have anysuitable number of transmitters 830 and receivers 835. Further, thetransmitter(s) 830 and the receiver(s) 835 may be any suitable type oftransmitters and receivers. Additionally, the transceiver 825 maysupport at least one network interface 840. Here, the at least onenetwork interface 840 facilitates communication with a RAN node, such asan eNB or gNB, for example using the “Uu” interface. Additionally, theat least one network interface 840 may include an interface used forcommunications with one or more network functions in the mobile corenetwork, such as a UPF, an AMF, and/or a SMF.

In one embodiment, the transceiver 825 includes a firsttransmitter/receiver pair used to communicate with a mobilecommunication network over licensed radio spectrum and a secondtransmitter/receiver pair used to communicate with a mobilecommunication network over unlicensed radio spectrum. In certainembodiments, the first transmitter/receiver pair used to communicatewith a mobile communication network over licensed radio spectrum and thesecond transmitter/receiver pair used to communicate with a mobilecommunication network over unlicensed radio spectrum may be combinedinto a single transceiver unit, for example a single chip performingfunctions for use with both licensed and unlicensed radio spectrum. Insome embodiments, the first transmitter/receiver pair and the secondtransmitter/receiver pair may share one or more hardware components. Forexample, certain transceivers 825, transmitters 830, and receivers 835may be implemented as physically separate components that access ashared hardware resource and/or software resource, such as for example,the network interface 840.

In various embodiments, one or more transmitters 830 and/or one or morereceivers 835 may be implemented and/or integrated into a singlehardware component, such as a multi-transceiver chip, asystem-on-a-chip, an application-specific integrated circuit (“ASIC”),or other type of hardware component. In certain embodiments, one or moretransmitters 830 and/or one or more receivers 835 may be implementedand/or integrated into a multi-chip module. In some embodiments, othercomponents such as the network interface 840 or other hardwarecomponents/circuits may be integrated with any number of transmitters830 and/or receivers 835 into a single chip. In such embodiment, thetransmitters 830 and receivers 835 may be logically configured as atransceiver 825 that uses one more common control signals or as modulartransmitters 830 and receivers 835 implemented in the same hardware chipor in a multi-chip module.

FIG. 9 depicts a base station apparatus 900 that may be used forgroupcast with beamformed selective transmission/retransmission m,according to embodiments of the disclosure. The base station apparatus900 may be one embodiment of the remote unit 105 or UE, described above.Furthermore, the base station apparatus 900 may include a processor 905,a memory 910, an input device 915, an output device 920, and atransceiver 925. In some embodiments, the input device 915 and theoutput device 920 are combined into a single device, such as atouchscreen. In certain embodiments, the base station apparatus 900 maynot include any input device 915 and/or output device 920. In variousembodiments, the base station apparatus 900 may include one or more of:the processor 905, the memory 910, and the transceiver 925, and may notinclude the input device 915 and/or the output device 920.

The processor 905, in one embodiment, may include any known controllercapable of executing computer-readable instructions and/or capable ofperforming logical operations. For example, the processor 905 may be amicrocontroller, a microprocessor, a CPU, a GPU, an auxiliary processingunit, a FPGA, or similar programmable controller. In some embodiments,the processor 905 executes instructions stored in the memory 910 toperform the methods and routines described herein. The processor 905 iscommunicatively coupled to the memory 910, the input device 915, theoutput device 920, and the transceiver 925.

In various embodiments, the base station apparatus 900 operatesaccording to the gNB/eNB behaviors described herein. Specifically, theprocessor 905 may configure one or more UEs with a sidelink groupcastHARQ retransmission profile. Thereafter, the UEs may select a sidelinkretransmission mode (e.g., N-unicast transmission with beamforming orGroupcast with partial beamsweeping) according to the configuredsidelink groupcast HARQ retransmission profile. As described above, thecriteria for sidelink retransmission mode selection may include thenumber of UEs sending NACK and/or the QoS priority of the initialgroupcast transmission.

In some embodiments, the processor 905 may configure one or more UEswith a pool of feedback resources for sidelink communication. In someembodiments, the processor 905 may determine location assistanceinformation for one or more UEs (e.g., vehicular UEs). In suchembodiments, the processor 905 may control the transceiver 925 to sendthe location assistance information to at least one UE using sidelinkcommunication, wherein the location assistance information is used bythe UE for beam selection and/or determining the number of beams to usefor data transmission.

The memory 910, in one embodiment, is a computer readable storagemedium. In some embodiments, the memory 910 includes volatile computerstorage media. For example, the memory 910 may include a RAM, includingdynamic RAM (“DRAM”), synchronous dynamic RAM (“SDRAM”), and/or staticRAM (“SRAM”). In some embodiments, the memory 910 includes non-volatilecomputer storage media. For example, the memory 910 may include a harddisk drive, a flash memory, or any other suitable non-volatile computerstorage device. In some embodiments, the memory 910 includes bothvolatile and non-volatile computer storage media.

In some embodiments, the memory 910 stores data related to groupcastwith beamformed selective transmission/retransmission. For example, thememory 910 may store HARQ resources, TA values, UE configurations, andthe like. In certain embodiments, the memory 910 also stores programcode and related data, such as an operating system or other controlleralgorithms operating on the remote unit 105.

The input device 915, in one embodiment, may include any known computerinput device including a touch panel, a button, a keyboard, a stylus, amicrophone, or the like. In some embodiments, the input device 915 maybe integrated with the output device 920, for example, as a touchscreenor similar touch-sensitive display. In some embodiments, the inputdevice 915 includes a touchscreen such that text may be input using avirtual keyboard displayed on the touchscreen and/or by handwriting onthe touchscreen. In some embodiments, the input device 915 includes twoor more different devices, such as a keyboard and a touch panel.

The output device 920, in one embodiment, is designed to output visual,audible, and/or haptic signals. In some embodiments, the output device920 includes an electronically controllable display or display devicecapable of outputting visual data to a user. For example, the outputdevice 920 may include, but is not limited to, an LCD display, an LEDdisplay, an OLED display, a projector, or similar display device capableof outputting images, text, or the like to a user. As another,non-limiting, example, the output device 920 may include a wearabledisplay separate from, but communicatively coupled to, the rest of thebase station apparatus 900, such as a smart watch, smart glasses, aheads-up display, or the like. Further, the output device 920 may be acomponent of a smart phone, a personal digital assistant, a television,a table computer, a notebook (laptop) computer, a personal computer, avehicle dashboard, or the like.

In certain embodiments, the output device 920 includes one or morespeakers for producing sound. For example, the output device 920 mayproduce an audible alert or notification (e.g., a beep or chime). Insome embodiments, the output device 920 includes one or more hapticdevices for producing vibrations, motion, or other haptic feedback. Insome embodiments, all or portions of the output device 920 may beintegrated with the input device 915. For example, the input device 915and output device 920 may form a touchscreen or similar touch-sensitivedisplay. In other embodiments, the output device 920 may be located nearthe input device 915.

The transceiver 925 includes at least transmitter 930 and at least onereceiver 935. One or more transmitters 930 may be used to communicatewith the UE, as described herein. Similarly, one or more receivers 935may be used to communicate with other network functions in the PLMN, asdescribed herein. Although only one transmitter 930 and one receiver 935are illustrated, the base station apparatus 900 may have any suitablenumber of transmitters 930 and receivers 935. Further, thetransmitter(s) 925 and the receiver(s) 930 may be any suitable type oftransmitters and receivers.

FIG. 10 depicts one embodiment of a method 1000 for selectiveretransmission of groupcast data, according to embodiments of thedisclosure. In various embodiments, the method 1000 is performed byremote unit 105, the Tx UE 205, and/or the user equipment apparatus 800,described above. In some embodiments, the method 1000 is performed by aprocessor, such as a microcontroller, a microprocessor, a CPU, a GPU, anauxiliary processing unit, a FPGA, or the like.

The method 1000 begins and transmits 1005 groupcast data via sidelinkcommunication to a set of UEs (e.g., Rx UEs 210). The method 1000includes receiving 1010 negative acknowledgement feedback via sidelinkcommunication from at least one UE of the set. Here, the negativeacknowledgement feedback indicate unsuccessful reception of thegroupcast data. The method 1000 includes determining 1015 aretransmission mode based on the received feedback. In some embodiments,the determination of the retransmission mode is determined based on anumber of UEs sending negative acknowledgement feedback. The method 1000includes selectively sending 1020 beamformed retransmission of thegroupcast data according to the determined retransmission mode. Themethod 1000 ends.

FIG. 11 depicts one embodiment of a method 1100 for selectiveretransmission of groupcast data, according to embodiments of thedisclosure. In various embodiments, the method 1100 is performed by theremote unit 105, the Rx UE 210, and/or the user equipment apparatus 800,described above. In some embodiments, the method 1100 is performed by aprocessor, such as a microcontroller, a microprocessor, a CPU, a GPU, anauxiliary processing unit, a FPGA, or the like.

The method 1100 begins and receives 1105 a groupcast signal from a TxUE. The method 1100 includes detecting 1110 the unsuccessfully decodingof the groupcast signal. The method 1100 includes sending 1115, to theTx UE, feedback that include a negative acknowledgment (“NACK”). Themethod 1100 includes receiving a retransmission from the Tx UE using aretransmission mode. The method 1100 ends.

FIG. 12 depicts one embodiment of a method 1200 for selectiveretransmission of groupcast data, according to embodiments of thedisclosure. In various embodiments, the method 1200 is performed by theremote unit 105, the Rx UE 210, and/or the user equipment apparatus 800,described above. In some embodiments, the method 1200 is performed by aprocessor, such as a microcontroller, a microprocessor, a CPU, a GPU, anauxiliary processing unit, a FPGA, or the like.

The method 1200 begins and receives 1205 (e.g., from a gNB) aconfiguration associated with a resource pool for PSFCH. The method 1200includes receiving 1210 groupcast data (e.g., from a Tx UE) viasidelink. The method 1200 includes determining 1215 HARQ feedback basedat least in part on the received groupcast data. The method 1200includes determining 1220 a PSFCH resource for the HARQ feedback basedat least in part on the resource pool for the PSFCH. The method 1200includes transmitting 1225 the HARQ feedback (e.g., to the Tx UE) usingthe determined PSFCH resource. The method 1200 ends.

Disclosed herein is a first apparatus for selective retransmission ofgroupcast data, according to embodiments of the disclosure. The firstapparatus may be implemented by the remote unit 105, the Tx UE 205,and/or the user equipment apparatus 800. The first apparatus includes atransceiver that transmits groupcast data via sidelink communication toa set of UEs (e.g., Rx UEs 210) and receives negative acknowledgementfeedback via sidelink communication from at least one UE of the set, thenegative acknowledgement feedback indicating unsuccessful reception ofthe groupcast data. The first apparatus includes a processor thatdetermines a retransmission mode based on a number of UEs sendingnegative acknowledgement feedback and controls the transceiver to sendselectively beamformed retransmission of the groupcast data according tothe determined retransmission mode.

In certain embodiments, the retransmission(s) of the groupcast datais/are only sent to those UEs that transmitted negative acknowledgementfeedback. In one embodiment, the retransmission mode is unicastretransmission with beamforming. In another embodiment, theretransmission mode is groupcast with partial beam sweeping. In someembodiments, determining the retransmission mode is further based on aQoS priority of the groupcast data.

In some embodiments, the transceiver receives a sidelink groupcast HARQretransmission profile from a base station in a mobile communicationnetwork. In various embodiments, the sidelink communication does notpass through the base station. In certain embodiments, the base stationindicates a pool of feedback resources for sidelink communication.

In some embodiments, the transceiver further transmits SCI to the set ofUEs. In certain embodiments, the SCI includes a data transmission indexand a transmission occasion. In certain embodiments, the SCI indicates aPSFCH format for feedback. In such embodiments, the at least one UEtransmits the negative acknowledgement using the indicated PSFCH format.

In some embodiments, receiving negative acknowledgement feedbackincludes receiving best beam information from the at least one UE. Insuch embodiments, the processor may select one or more beams using thebest beam information. In further embodiments, sending selectivelybeamformed retransmission of the groupcast data includes the transceiverretransmitting on the selected one or more beams.

In some embodiments, receiving negative acknowledgement feedbackincludes receiving location information for the at least one UE. In suchembodiments, the processor may select one or more beams using thelocation information. In further embodiments, sending selectivelybeamformed retransmission of the groupcast data includes the transceiverretransmitting on the selected one or more beams.

In various embodiments, transmitting the groupcast data includestransmitting two or more data TB s simultaneously using differentantenna panels.

Disclosed herein is a first method for selective retransmission ofgroupcast data, according to embodiments of the disclosure. The firstmethod may be performed by the remote unit 105, the Tx UE 205, and/orthe user equipment apparatus 800. The first method includes transmittinggroupcast data via sidelink communication to a set of UEs (e.g., Rx UEs210) and receiving negative acknowledgement feedback via sidelinkcommunication from at least one UE of the set. Here, the negativeacknowledgement feedback indicating unsuccessful reception of thegroupcast data. The first method includes determining a retransmissionmode based on a number of UEs sending negative acknowledgement feedbackand sending selectively beamformed retransmission of the groupcast dataaccording to the determined retransmission mode.

In certain embodiments, the retransmission(s) of the groupcast datais/are only sent to those UEs that transmitted negative acknowledgementfeedback. In one embodiment, the retransmission mode is unicastretransmission with beamforming. In another embodiment, theretransmission mode is groupcast with partial beam sweeping. In someembodiments, determining the retransmission mode is further based on aQoS priority of the groupcast data.

In some embodiments, the first method further includes receiving asidelink groupcast HARQ retransmission profile from a base station in amobile communication network. In various embodiments, the sidelinkcommunication does not pass through the base station.

In some embodiments, the first method further includes transmitting SCIto the set of UEs. In certain embodiments, the sidelink controlinformation includes a data transmission index and a transmissionoccasion. In certain embodiments, the sidelink control informationindicates a PSFCH format for feedback, wherein the at least one UEtransmits the negative acknowledgement using the indicated PSFCH format.

In some embodiments, receiving negative acknowledgement feedbackincludes receiving best beam information from the at least one UE. Insuch embodiments, sending selectively beamformed retransmission of thegroupcast data includes retransmitting on one or more beams selectedusing the best beam information.

In some embodiments, receiving negative acknowledgement feedbackincludes receiving location information for the at least one UE. In suchembodiments, sending selectively beamformed retransmission of thegroupcast data includes retransmitting on one or more beams selectedusing the location information.

In various embodiments, transmitting the groupcast data includestransmitting two or more data TB s simultaneously using differentantenna panels.

Disclosed herein is a second apparatus for selective retransmission ofgroupcast data, according to embodiments of the disclosure. The secondapparatus may be implemented by the remote unit 105, the Rx UE 210,and/or the user equipment apparatus 800. The second apparatus includes atransceiver that receives a groupcast signal from a Tx UE and aprocessor that detects the unsuccessful decoding the groupcast signal.The processor determines best beam information and sends feedback to theTx UE via the transceiver. Here, the feedback includes a negativeacknowledgement and the best beam information.

In some embodiments, the transceiver receives a sidelink referencesignal associated with the groupcast signal, wherein the processorderives the best beam information using the sidelink reference signal.In some embodiments, the feedback includes sidelink channel stateinformation.

In some embodiments, the transceiver receives SCI prior to receiving thegroupcast signal. In such embodiments, the SCI is received together witha sidelink reference signal associated with the groupcast signal. Insome embodiments sending feedback to the Tx UE includes transmitting thefeedback towards the Tx UE using beam sweeping.

Disclosed herein is a second method for selective retransmission ofgroupcast data, according to embodiments of the disclosure. The secondmethod may be performed by the remote unit 105, the Rx UE 210, and/orthe user equipment apparatus 800. The second method includes receiving agroupcast signal from a Tx UE and unsuccessfully decoding the groupcastsignal. In response to the unsuccessful decoding, the second methodincludes determining best beam information and sending feedback to theTx UE. Here, the feedback includes a negative acknowledgement and thebest beam information.

In some embodiments, the second method includes receiving a sidelinkreference signal associated with the groupcast signal, wherein the bestbeam information is derived using the sidelink reference signal. In someembodiments, the feedback includes sidelink channel state information.

In some embodiments, the second method includes receiving SCI prior toreceiving the groupcast signal. In certain embodiments, the SCI isreceived together with a sidelink reference signal associated with thegroupcast signal. In some embodiments, sending feedback to the Tx UEincludes transmitting the feedback towards the Tx UE using beamsweeping.

Disclosed herein is a third apparatus for selective retransmission ofgroupcast data, according to embodiments of the disclosure. The thirdapparatus may be implemented by the remote unit 105, the Tx UE 205,and/or the user equipment apparatus 800. The third apparatus includes aprocessor coupled to a transceiver, the processor configured to causethe third apparatus to A) transmit groupcast data via sidelinkcommunication to a set of UEs (e.g., Rx UEs 210); B) receive negativeacknowledgement feedback via sidelink communication from at least one UEof the set, the negative acknowledgement feedback indicatingunsuccessful reception of the groupcast data; C) determine aretransmission mode based on the feedback; and D) send selectivelybeamformed retransmission(s) of the groupcast data according to thedetermined retransmission mode.

In some embodiments, the initial transmission of the groupcast data isperformed using a first cast-type and the determined retransmission modeindicates a second cast-type different than the first cast-type. In oneembodiment, the second cast-type is unicast retransmission withbeamforming. In another embodiment, the second cast-type is groupcastwith partial beam sweeping.

In certain embodiments, the retransmission(s) of the groupcast datais/are only sent to those UEs that transmitted negative acknowledgementfeedback. In some embodiments, determining the retransmission mode isfurther based on a QoS priority of the groupcast data.

In some embodiments, the processor is further configured to cause thethird apparatus to receive a sidelink groupcast HARQ retransmissionprofile from a base station in a mobile communication network. Invarious embodiments, the sidelink communication does not pass throughthe base station. In certain embodiments, the base station indicates apool of feedback resources for sidelink communication.

In some embodiments, the processor is further configured to cause thethird apparatus to transmit SCI to the set of UEs. In certainembodiments, the SCI includes a data transmission index and atransmission occasion. In certain embodiments, the SCI indicates a PSFCHformat for feedback. In such embodiments, the third apparatus receivesthe negative acknowledgement feedback from the at least one UE using theindicated PSFCH format.

In some embodiments, to receive the negative acknowledgement feedback,the processor is configured to cause the third apparatus to receive bestbeam information from the at least one UE. In such embodiments, theprocessor is further configured to cause the third apparatus to selectone or more beams using the best beam information. In furtherembodiments, to send the selectively beamformed retransmission of thegroupcast data, the processor is configured to cause the third apparatusto retransmit on the selected one or more beams.

In some embodiments, to receive the negative acknowledgement feedback,the processor is configured to cause the third apparatus to receivelocation information for the at least one UE. In such embodiments, theprocessor may select one or more beams using the location information.In further embodiments, to send the selectively beamformedretransmission of the groupcast data, the processor is configured tocause the third apparatus to retransmit on the selected one or morebeams.

In some embodiments, the processor is further configured to cause thethird apparatus to implicitly determine a best beam for retransmissionbased on information of a beam used by a respective UE from the set ofUEs to transit HARQ feedback for the groupcast data. In variousembodiments, to transmit the groupcast data, the processor is configuredto transmit two or more data TB s simultaneously using different antennapanels. In some embodiments, the processor is further configured tocause the apparatus to determine the retransmission mode based on anumber of UEs sending a respective negative acknowledgement feedback.

Disclosed herein is a third method for selective retransmission ofgroupcast data, according to embodiments of the disclosure. The thirdmethod may be performed by the remote unit 105, the Tx UE 205, and/orthe user equipment apparatus 800. The third method includes transmittinggroupcast data via sidelink communication to a set of UEs (e.g., Rx UEs210) and receiving negative acknowledgement feedback via sidelinkcommunication from at least one UE of the set. Here, the negativeacknowledgement feedback indicating unsuccessful reception of thegroupcast data. The third method includes determining a retransmissionmode based on the received feedback and sending selectively beamformedretransmission(s) of the groupcast data according to the determinedretransmission mode.

In some embodiments, the initial transmission of the groupcast data isperformed using a first cast-type and the determined retransmission modeindicates a second cast-type different than the first cast-type. In oneembodiment, the second cast-type is unicast retransmission withbeamforming. In another embodiment, the second cast-type is groupcastwith partial beam sweeping.

In certain embodiments, the retransmission(s) of the groupcast datais/are only sent to those UEs that transmitted negative acknowledgementfeedback. In some embodiments, determining the retransmission mode isfurther based on a QoS priority of the groupcast data.

In some embodiments, the third method further includes receiving asidelink groupcast HARQ retransmission profile from a base station in amobile communication network. In various embodiments, the sidelinkcommunication does not pass through the base station. In certainembodiments, the base station indicates a pool of feedback resources forsidelink communication.

In some embodiments, the third method further includes transmitting SCIto the set of UEs. In certain embodiments, the SCI includes a datatransmission index and a transmission occasion. In certain embodiments,the SCI indicates a PSFCH format for feedback. In such embodiments, thenegative acknowledgement feedback is received from the at least one UEusing the indicated PSFCH format.

In some embodiments, receiving the negative acknowledgement feedbackcomprises receiving best beam information from the at least one UE. Insuch embodiments, the third method further includes selecting one ormore beams using the best beam information. In further embodiments,sending the selectively beamformed retransmission of the groupcast datacomprises retransmitting on the selected one or more beams.

In some embodiments, receiving the negative acknowledgement feedbackcomprises receiving location information for the at least one UE. Insuch embodiments, the third method further includes using the locationinformation. In further embodiments, sending the selectively beamformedretransmission of the groupcast data comprises retransmitting on theselected one or more beams.

In some embodiments, implicitly determining a best beam forretransmission based on information of a beam used by a respective UEfrom the set of UEs to transit HARQ feedback for the groupcast data. Invarious embodiments, transmitting the groupcast data includestransmitting two or more data TB s simultaneously using differentantenna panels. In some embodiments, the third method further includesdetermining the retransmission mode based on a number of UEs sending arespective negative acknowledgement feedback.

Disclosed herein is a fourth apparatus for selective retransmission ofgroupcast data, according to embodiments of the disclosure. The fourthapparatus may be implemented by the remote unit 105, the Rx UE 210,and/or the user equipment apparatus 800. The fourth apparatus includes aprocessor coupled to a transceiver, the processor configured to causethe fourth apparatus to A) receive a groupcast signal from a Tx UE; B)detect the unsuccessful decoding the groupcast signal; C) send feedbackto the Tx UE that includes a negative acknowledgement; and D) receive aretransmission from the Tx UE using a retransmission mode.

In some embodiments, the initial reception of the groupcast data isperformed using a first cast-type and the retransmission mode comprisesa second cast-type different than the first cast-type. In oneembodiment, the second cast-type is unicast retransmission withbeamforming. In another embodiment, the second cast-type is groupcastwith partial beam sweeping.

In some embodiments, the processor is further configured to cause thefourth apparatus to A) receive a sidelink reference signal associatedwith the groupcast signal; and B) derive sidelink channel stateinformation using the sidelink reference signal. In some embodiments,the feedback includes sidelink channel state information. In someembodiments, the sidelink channel state information includes best beaminformation.

In some embodiments, the transceiver receives SCI prior to receiving thegroupcast signal. In such embodiments, the SCI is received together witha sidelink reference signal associated with the groupcast signal. Insome embodiments, to send the feedback to the Tx UE, the processor isconfigured to cause the fourth apparatus to transmit the feedbacktowards the Tx UE using beam sweeping.

Disclosed herein is a fourth method for selective retransmission ofgroupcast data, according to embodiments of the disclosure. The fourthmethod may be performed by the remote unit 105, the Rx UE 210, and/orthe user equipment apparatus 800. The fourth method includes receiving agroupcast signal from a Tx UE and unsuccessfully decoding the groupcastsignal. In response to the unsuccessful decoding, the fourth methodincludes sending feedback to the Tx UE and receiving a retransmissionfrom the Tx UE using a retransmission mode. Here, the feedback includesa negative acknowledgement and the best beam information.

In some embodiments, the initial reception of the groupcast data isperformed using a first cast-type and the retransmission mode comprisesa second cast-type different than the first cast-type. In oneembodiment, the second cast-type is unicast retransmission withbeamforming. In another embodiment, the second cast-type is groupcastwith partial beam sweeping.

In some embodiments, the fourth method includes receiving a sidelinkreference signal associated with the groupcast signal, wherein sidelinkchannel state information is derived using the sidelink referencesignal. In some embodiments, the feedback includes sidelink channelstate information. In some embodiments, the sidelink channel stateinformation includes best beam information.

In some embodiments, the fourth method includes receiving SCI prior toreceiving the groupcast signal. In certain embodiments, the SCI isreceived together with a sidelink reference signal associated with thegroupcast signal. In some embodiments, sending feedback to the Tx UEincludes transmitting the feedback towards the Tx UE using beamsweeping.

Disclosed herein is a fifth method, in accordance with aspects of thepresent disclosure. The fifth method may be performed by the remote unit105, the Rx UE 210, and/or the user equipment apparatus 800. The fifthmethod includes receiving (e.g., from a gNB) a configuration associatedwith a resource pool for PSFCH. The fifth method includes receivinggroupcast data (e.g., from a Tx UE) via sidelink and determining HARQfeedback based at least in part on the received groupcast data. Thefifth method includes determining a PSFCH resource for the HARQ feedbackbased at least in part on the resource pool for the PSFCH andtransmitting the HARQ feedback (e.g., to the Tx UE) using the determinedPSFCH resource.

In some embodiments, receiving the groupcast data includes receiving aPSCCH transmission comprising SCI, where the SCI indicates a groupcasttransmission. In certain embodiments, the SCI indicates a set of valuesfor the HARQ feedback, wherein the set of values includes a first valueindicating a positive acknowledgement (ACK) and a second valueindicating a negative acknowledgement (NACK). In certain embodiments,the SCI indicates a data transmission index and a transmission occasion.

In some embodiments, to determine the PSFCH resource, the fifth methodincludes selecting the PSFCH resource from a subset of the resourcepool. In certain embodiments, the determined PSFCH resource is selectedbased on a member identifier associated with the UE. In someembodiments, the determined PSFCH resource is within a PSFCH resourceset configured within the resource pool, where the PSFCH resource set issemi-statically assigned to the UE for the HARQ feedback.

In certain embodiments, the subset of the resource pool is based on aQoS priority of the groupcast data. In one embodiment, the fifth methodincludes receiving a PSCCH transmission comprising SCI associated withthe groupcast data, where the SCI indicates the QoS priority of thegroupcast data.

In certain embodiments, the resource pool is configured with a firstpool of PSFCH resources, and wherein the subset of the resource poolcomprises a second pool of PSFCH resources within the first pool ofPSFCH resources. In one embodiment, the second pool of PSFCH resourcesis determined based on SCI. In another embodiment, the second pool ofPSFCH resources is indicated (e.g., provided) by a network entity (e.g.,the gNB).

Disclosed herein is a UE that performs fifth method, in accordance withaspects of the present disclosure. The UE may include at least onememory and at least one processor coupled with the at least one memoryand configured to perform the fifth method. Specifically, the at leastone processor may be configured to cause the UE to: A) receive (e.g.,from a gNB) a configuration associated with a resource pool for PSFCH;B) receive groupcast data (e.g., from a Tx UE) via sidelink; C)determine HARQ feedback based at least in part on the received groupcastdata; D) determine a PSFCH resource for the HARQ feedback based at leastin part on the resource pool for the PSFCH; and E) transmit the HARQfeedback (e.g., to the Tx UE) using the determined PSFCH resource.

In some embodiments, to receive the groupcast data, the at least oneprocessor is configured to cause the UE to receive a PSCCH transmissioncomprising SCI, where the SCI indicates a groupcast transmission. Incertain embodiments, the SCI indicates a set of values for the HARQfeedback, wherein the set of values includes a first value indicating anACK and a second value indicating a NACK. In certain embodiments, theSCI indicates a data transmission index and a transmission occasion.

In some embodiments, to determine the PSFCH resource, the at least oneprocessor is configured to cause the UE to select the PSFCH resourcefrom a subset of the resource pool. In certain embodiments, thedetermined PSFCH resource is selected based on a member identifierassociated with the UE. In some embodiments, the determined PSFCHresource is within a PSFCH resource set configured within the resourcepool, where the PSFCH resource set is semi-statically assigned to the UEfor the HARQ feedback.

In certain embodiments, the subset of the resource pool is based on aQoS priority of the groupcast data. In one embodiment, the at least oneprocessor is configured to cause the UE to receive a PSCCH transmissioncomprising SCI associated with the groupcast data, where the SCIindicates the QoS priority of the groupcast data.

In certain embodiments, the resource pool is configured with a firstpool of PSFCH resources, and wherein the subset of the resource poolcomprises a second pool of PSFCH resources within the first pool ofPSFCH resources. In one embodiment, the at least one processor isconfigured to cause the UE to determine the second pool of PSFCHresources based on SCI. In another embodiment, the second pool of PSFCHresources is indicated (e.g., provided) by a network entity (e.g., thegNB).

Disclosed herein is a processor for wireless communication that performsfifth method, in accordance with aspects of the present disclosure. Theprocessor may include at least one controller coupled with at least onememory and configured to perform the fifth method. Specifically, the atleast one controller may be configured to cause the processor to: A)receive (e.g., from a gNB) a configuration associated with a resourcepool for PSFCH; B) receive groupcast data (e.g., from a Tx UE) viasidelink; C) determine HARQ feedback based at least in part on thereceived groupcast data; D) determine a PSFCH resource for the HARQfeedback based at least in part on the resource pool for the PSFCH; andE) transmit the HARQ feedback (e.g., to the Tx UE) using the determinedPSFCH resource.

In some embodiments, to receive the groupcast data, the at least onecontroller is configured to cause the processor to receive a PSCCHtransmission comprising SCI, where the SCI indicates a groupcasttransmission. In certain embodiments, the SCI indicates a set of valuesfor the HARQ feedback, wherein the set of values includes a first valueindicating a ACK and a second value indicating a NACK. In certainembodiments, the SCI indicates a data transmission index and atransmission occasion.

In some embodiments, to determine the PSFCH resource, the at least onecontroller is configured to cause the processor to select the PSFCHresource from a subset of the resource pool. In certain embodiments, thedetermined PSFCH resource is selected based on a member identifierassociated with the processor.

In certain embodiments, the resource pool is configured with a firstpool of PSFCH resources, and wherein the subset of the resource poolcomprises a second pool of PSFCH resources within the first pool ofPSFCH resources. In one embodiment, the at least one controller isconfigured to cause the processor to determine the second pool of PSFCHresources based on SCI. In another embodiment, the second pool of PSFCHresources is indicated (e.g., provided) by a network entity (e.g., thegNB).

In some embodiments, the determined PSFCH resource is within a PSFCHresource set configured within the resource pool, where the PSFCHresource set is semi-statically assigned to the UE for the HARQfeedback.

Embodiments may be practiced in other specific forms. The describedembodiments are to be considered in all respects only as illustrativeand not restrictive. The scope of the invention is, therefore, indicatedby the appended claims rather than by the foregoing description. Allchanges which come within the meaning and range of equivalency of theclaims are to be embraced within their scope.

1. A user equipment (UE) for wireless communication, comprising: atleast one memory; and at least one processor coupled with the at leastone memory and configured to cause the UE to: receive a configurationassociated with a resource pool for physical sidelink feedback channel(PSFCH); receive groupcast data via sidelink; determine hybrid automaticrepeat request (HARQ) feedback based at least in part on the receivedgroupcast data; determine a PSFCH resource for the HARQ feedback basedat least in part on the resource pool for the PSFCH; and transmit theHARQ feedback using the determined PSFCH resource.
 2. The UE of claim 1,wherein to receive the groupcast data, the at least one processor isconfigured to cause the UE to receive a physical sidelink controlchannel (PSCCH) transmission comprising sidelink control information(SCI), and wherein the SCI indicates a groupcast transmission.
 3. The UEof claim 2, wherein the SCI indicates a set of values for the HARQfeedback, wherein the set of values includes a first value indicating apositive acknowledgement (ACK) and a second value indicating a negativeacknowledgement (NACK).
 4. The UE of claim 2, wherein the SCI indicatesa data transmission index and a transmission occasion.
 5. The UE ofclaim 1, wherein to determine the PSFCH resource, the at least oneprocessor is configured to cause the UE to select the PSFCH resourcefrom a subset of the resource pool.
 6. The UE of claim 5, wherein thesubset of the resource pool is based on a Quality of Service (QoS)priority of the groupcast data.
 7. The UE of claim 6, wherein to receivethe groupcast data, the at least one processor is configured to causethe UE to receive a physical sidelink control channel (PSCCH)transmission comprising sidelink control information (SCI), and whereinthe SCI indicates the QoS priority of the groupcast data.
 8. The UE ofclaim 5, wherein the determined PSFCH resource is selected based on amember identifier associated with the UE.
 9. The UE of claim 5, whereinthe resource pool is configured with a first pool of PSFCH resources,and wherein the subset of the resource pool comprises a second pool ofPSFCH resources within the first pool of PSFCH resources.
 10. The UE ofclaim 9, wherein the second pool of PSFCH resources is determined basedon sidelink control information (SCI).
 11. The UE of claim 9, whereinthe second pool of PSFCH resources is indicated by a network entity. 12.The UE of claim 1, wherein the determined PSFCH resource is within aPSFCH resource set configured within the resource pool, wherein thePSFCH resource set is semi-statically assigned to the UE for the HARQfeedback.
 13. A processor for wireless communication, comprising: atleast one controller coupled with at least one memory and configured tocause the processor to: receive a configuration associated with aresource pool for physical sidelink feedback channel (PSFCH); receivegroupcast data via sidelink communication; determine hybrid automaticrepeat request (HARQ) feedback based at least in part on the receivedgroupcast data; determine a PSFCH resource for the HARQ feedback basedat least in part on the resource pool for the PSFCH; and transmit theHARQ feedback using the determined PSFCH resource.
 14. The processor ofclaim 13, wherein to receive the groupcast data, the at least onecontroller is configured to cause the processor to receive a physicalsidelink control channel (PSCCH) transmission comprising sidelinkcontrol information (SCI), and wherein the SCI indicates a groupcasttransmission.
 15. The processor of claim 14, wherein the SCI indicates aset of values for the HARQ feedback, wherein the set of possible valuesincludes a first value indicating a positive acknowledgement (ACK) and asecond values indicating a negative acknowledgement (NACK).
 16. Theprocessor of claim 14, wherein the SCI indicates a data transmissionindex and a transmission occasion.
 17. The processor of claim 13,wherein to determine the PSFCH resource, the at least one controller isconfigured to cause the processor to select the PSFCH resource from asubset of the resource pool.
 18. The processor of claim 17, wherein thedetermined PSFCH resource is selected based on a member identifierassociated with the processor.
 19. The processor of claim 17, whereinthe resource pool is configured with a first pool of PSFCH resources,wherein the subset of the resource pool comprises a second pool of PSFCHresources within the first pool of PSFCH resources, and wherein thefirst pool of PSFCH resources is semi-statically assigned to theprocessor for the HARQ feedback.
 20. A method performed by a userequipment (UE), the method comprising: receiving a configurationassociated with a resource pool for physical sidelink feedback channel(PSFCH); receiving groupcast data via sidelink communication;determining hybrid automatic repeat request (HARQ) feedback based atleast in part on the received groupcast data; determining a PSFCHresource for the HARQ feedback based at least in part on the resourcepool for the PSFCH; and transmitting the HARQ feedback using thedetermined PSFCH resource.